A common technique to improve search mode performance in radar signal processing involves the generation of simultaneous receive beams. The technique enables an operator to scan a wide area in a short amount of time. The generation of simultaneous receive beams is typically done using an antenna consisting of multiple subarrays. Since subarray spacings are typically large compared to the half-wavelength, grating lobes arise whenever a receive beam is pointed off angle from the transmit beam direction. These grating lobes are often close to the antenna mainlobe and much larger than the antenna sidelobes. Many techniques have been used in the past to architect the antenna to reduce the size of the grating lobes or minimize its impact on the radar returns. As successful as these techniques may be, residual grating lobes and sidelobes remain and target returns from these regions can register as false hits coming from the mainlobe if not eliminated. A need therefore exists for improved methods and systems for distinguishing mainlobe detections from grating lobe and sidelobe detections.
Methods and systems to distinguish mainlobe detections from grating lobe and sidelobe detections have existed, but typically they involve added antenna and receiver architecture, such as the use of guard horns or frequency diversity. A technique that does not require added antenna and receiver architecture used post-processing digital filtering and correlations.